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Title: Symmetry and optical spectra: a 'silent' 1:2 Np(V)/oxydiacetatecomplex

Abstract

No abstract prepared.

Authors:
; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director. Office of Science. Basic EnergySciences
OSTI Identifier:
932985
Report Number(s):
LBNL-63469
R&D Project: 403006; BnR: KC0302030; TRN: US200814%%194
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemical Communications; Journal Volume: 0; Journal Issue: 0; Related Information: Journal Publication Date: 2007
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; SPECTRA; SYMMETRY; CHEMISTRY

Citation Formats

Tian, Guoxin, Rao, Linfeng, and Oliver, Allen. Symmetry and optical spectra: a 'silent' 1:2 Np(V)/oxydiacetatecomplex. United States: N. p., 2007. Web. doi:10.1039/b706825e.
Tian, Guoxin, Rao, Linfeng, & Oliver, Allen. Symmetry and optical spectra: a 'silent' 1:2 Np(V)/oxydiacetatecomplex. United States. doi:10.1039/b706825e.
Tian, Guoxin, Rao, Linfeng, and Oliver, Allen. Thu . "Symmetry and optical spectra: a 'silent' 1:2 Np(V)/oxydiacetatecomplex". United States. doi:10.1039/b706825e.
@article{osti_932985,
title = {Symmetry and optical spectra: a 'silent' 1:2 Np(V)/oxydiacetatecomplex},
author = {Tian, Guoxin and Rao, Linfeng and Oliver, Allen},
abstractNote = {No abstract prepared.},
doi = {10.1039/b706825e},
journal = {Chemical Communications},
number = 0,
volume = 0,
place = {United States},
year = {Thu Mar 01 00:00:00 EST 2007},
month = {Thu Mar 01 00:00:00 EST 2007}
}
  • The chemistry of NO with transition metals is of great importance in synthesis, catalysis, surface science, and especially environmental science, as NO{sub x} compounds are significant pollutants from automobile exhausts. Laser-ablated vanadium atoms have been reacted with NO molecules during condensation in excess argon. Absorptions due to NVO (998.1, 906.4 cm{sup {minus}1}), V-{eta}{sup 1}-NO (1606.0 cm{sup {minus}1}), V-{eta}{sup 2}-NO (1075.7 cm{sup {minus}1}) and V-({eta}{sup 2}-NO){sub 2} (1119.6, 1153.8 cm{sup {minus}1}) are observed and identified via isotopic substitution and DFT calculations. Higher nitrosyls are also formed on annealing. On the basis of the observed isotopic splitting, bands at 1614.5 and 1736.8more » cm{sup {minus}1} are assigned to antisymmetric and symmetric N-O vibrations of the C{sub 2{nu}} dinitrosyl V(NO){sub 2}, and 1715.1 and 1850.6 cm{sup {minus}1} bands are assigned to the analogous vibrations of V(NO){sub 3} with C{sub 3{nu}} symmetry. The observation of (VO), (N{sub 2}O) and (N{sub 2}), (VO{sub 2}) complexes suggests that V atoms also react with (NO){sub 2} in these experiments.« less
  • For the selection of the optimum conditions of coulometric titration of Np(VI)--Np(IV) by electrogenerated Fe(II) ions, the rate constants (k/sub d/) of the disproportionation of Np(V) and the real potentials (E/sub 0//sup p/) of the couples Np(VI)--Np(V), Np(VI)--Np(IV), Np(V)--Np(IV), and Fe(III)--Fe(II) were determined in solutions of nMH/sub 2/SO/sub 4/ + mMH/sub 3/PO/sub 4/ at (n + m) from 3 to 8. It was shown that k/sub d/ increases in proportion to the fourth power of the H/sub 2/SO/sub 4/ concentration in solution at a constant concentration of H/sub 3/PO/sub 4/. Approximately the same dependence on the H/sub 3/PO/sub 4/ concentrationmore » is observed. The maximum value of k/sub d/ (1.8 x 10/sup 5/ M/sup -1/ x min/sup -1/) was obtained in a medium of 4MH/sub 2/SO/sub 4/ + 4MH/sub 3/PO/sub 4/. A linear correlation was established between the values of k/sub d/ and E/sub 0//sup p/ of neptunium couples (the coefficient of correlation is equal to 0.98). This relationship is expressed in a broad range of variation of k/sub d/ (from 1.2 x 10/sup -6/ to 1.8 x 10/sup 5/ M/sup -1/ x min/sup -1/) by the equation E/sub 0//sup p/ = 1.036 + B log k/sub d/ (B = -0.0194, 0.0163, and 0.053 for the couples Np(VI)--Np(V), Np(VI)--Np(IV), and Np(V)--Np(IV), respectively). The results of the investigations permit one to select the composition of the supporting electrolyte, in which the reaction Np(VI) + 2Fe(II) = Np(IV) + 2Fe(III) will proceed at a rate sufficient for analytical purposes.« less
  • Complexes of Np(V)-Cr(III) and Np(V)-Rh(III) were prepared, and the complexes were separated from the uncomplexed ions by ion exchange. The Mossbauer spectral study of these complexes is reported. A structure has been suggested for the complexes that involves substitution of the NpO/sub 2//sup +/ ion for a water molecule in the first coordination sphere of the hexaaquochromium(III) and of the hexaaquorhodium(III) ion. The magnetic splitting in the spectra of the Np(V)-Cr(III) complex and the lack of magnetic splitting for the major fraction of the Np(V)-Rh(III) complex are consistent with the suggested structure. (BLM)
  • The reaction of NpO{sub 2} with SeO{sub 2} in the presence of CsCl at 180 {sup o}C results in the formation of Np(NpO{sub 2}){sub 2}(SeO{sub 3}){sub 3} (1). The structure of 1 consists of three crystallographically unique Np centers with three different coordination environments in two different oxidation states. Np(1) is found in a neptunyl(V), ONpO{sup +}, unit that is further ligated in the equatorial plane by three chelating SeO{sub 3}{sup 2-} anions to create a hexagonal bipyramidal NpO{sub 8} unit. A second neptunyl(V) cation also occurs for Np(2); it is bound by four bridging selenite anions and by themore » oxo atom from the Np(1) neptunyl cation to form a pentagonal bipyramidal, NpO{sub 7}, unit. The third neptunium center, Np(3), which contains Np(IV), is found in a distorted NpO{sub 8} dodecahedron. Np(3) is bound by five bridging selenite anions and by three neptunyl units via cation-cation interactions. The NpO{sub 7} pentagonal bipyramids and NpO{sub 8} hexagonal bipyramids share both corners and edges. Both of these polyhedra share corners via cation-cation interactions with the NpO{sub 8} dodecahedra creating a three-dimensional structure with small channels that house the stereochemically active lone pair of electrons on the selenite anions. Magnetic susceptibility data follow Curie-Weiss behavior over the entire temperature range measured (5 {<=} T {<=} 320 K). The effective moment, {mu}{sub eff} = 2.28 {mu}{sub B}, which represents an average over the three crystallographically inequivalent Np atoms, is within the expected range of values. There is no evidence of long-range ordering of the Np moments at temperatures down to 5 K, consistent with the negligible Weiss constant determined from fitting the susceptibility data. Crystallographic data: 1, orthorhombic, space group Pbca, a = 10.6216(5), b = 11.9695(6), and c = 17.8084(8) {angstrom} and Z = 8 (T = 193 K).« less